I'm having the same issue, suddenly OBS won't launch. Just insta-crashes.
Last stream I installed and tested out the CLR Browser plugin, which worked fantastically. This is one of only two changes I can think of that would affect it, the other being a codec update via the App Store that came down a day or two ago.
I've tried restarting, reinstalling OBS (without uninstalling, I don't want to lose all my scenes), removing the CLR Browser plugin using their uninstall script, running the Apple Diagnostic tool (no issues), etc.
I've attached a text file of what happens if I *manually* execute the OBS file in ./Contents/MacOS and it looks like a segfault when loading scenes :/
It also *used* to generate diagnostic repots in /Library/Logs/DiagnosticReports when it crashed but doesn't seem to anymore so I don't have one that I can attach :/
I'm going to try a full uninstall (including wiping scenes and plugins) and report back.